The 2014 SRT Viper line-up has been extended with the addition of a new mid-range Grand Touring option.

Unveiled at the Detroit motor show today, the 2014 SRT Viper GT features upgraded trim and more equipment.

Performance-related upgrades come in the form of a new five-mode electronic stability control - including 'Full-off' and 'rain' settings - and electrically adjustable Bilstein 'DampTronic' select suspension. Previously, these were only available on range-topping GTS models.

Leather seats are also standard on GT models, replacing the conventional cloth or optional part-leather seats. Buyers can opt for red, black or caramel finishes.

Pricing has yet to be announced but SRT says that the new GT is designed to bridge the gap between the entry-level Viper and the GTS model. The standard SRT Viper costs £62,214, the GTS £75,873. Consequently it's likely the SRT Viper GT, in the US market at least, will cost around £70,000.

Mechanically the SRT Viper GT remains otherwise unchanged, featuring a 640bhp 8.4-litre V10. Its top speed is claimed to be 206mph, and the 0-60mph sprint is reputed to be dispatched in less than 4.0sec.

Additionally, a new 'Stryker' green finish now offered and will be available on Viper GTS and GT models. GT models in particular will only be offered in Styker green and 'Venom' black.

"We're continuing to develop and build unique, low-volume, special-edition colours for the Viper that adds to the exclusivity of our American-built flagship supercar," said Ralph Gilles, President and CEO, SRT Brand and Motorsports.

"The application of the new Stryker Green exterior paint is a very detailed and intricate process, taking approximately eight hours to complete. The process first starts with a base colour coat followed by a green-tinted mid-coat and topped off with a clear finish."

The show car at Detroit, pictured above, will also serve to display some of Mopar's high-performance accessories and parts. Upgrades include a prototype aerodynamic package, featuring a carbon fibre rear wing and extended front corner splitters.

SRT's Viper line-up has also recently been extended with the new track-focussed Viper TA.